1. Field of the Invention
The disclosed invention generally relates to an apparatus for mixing slurries such as coal tar and asphalt based sealers. More particularly, the disclosed invention relates to an apparatus and associated method for mixing slurries by way of air-pulse agitation.
2. Brief Description of the Prior Art
Conventional methods and systems for mixing slurries such as coal tar and asphalt based sealers have incorporated mechanical mixing implements such as paddles. Less conventional methods include air or bubble-action agitation of the slurry mixture. While paddle-type slurry mixers may well function to properly mix a slurry into a uniform mixture, the machinery is often costly, complicated, and requires a great deal of maintenance. Air-based slurry mixing systems fare no better than their paddle mixing counterparts in terms of cost, complexity and inherent need for high levels of maintenance and care. Those systems that have been simplified in design so as to overcome the cost and complexity-related difficulties attendant to such designs often prove ineffectual for properly mixing the slurries. Some of the more pertinent art relating to paddle-type mixers, air-type mixers and the like is briefly set forth hereinafter.
U.S. Pat. No. 3,953,003 ('003 patent), which issued to Mahig, discloses a Tank Provided with Pneumatic Mixing Pipe. The '003 patent teaches a container adapted to thoroughly mix fluid material, especially suspensions, comprising a tank provided with a vertical mixing pipe, a vertical air lifting pipe, a gas collecting chamber located at the upper end of the mixing pipe, and a connecting pipe affixed at one end to the collecting chamber and communicating therewith and affixed at its other end to the bottom of the air lifting pipe and communicating therewith.
U.S. Pat. No. 4,298,287 ('287 patent), which issued to McCarter, III et al., discloses a Center Draft Asphaltic Concrete Drum Mixer. The '287 patent teaches a continuous drum mix asphalt plant wherein dust is exhausted from an intermediate zone of the drum mixer between its drying and mixing zones. The dust is exhausted radially through openings into a collection housing, which communicates with a dust collector and exhaust blower. An end housing at the discharge end of the drum communicates with the same dust collector and blower. Dampers are provided to control the relative proportion of air exhausted from the drum through the respective housings. Aggregate deflectors on the interior wall of the drum at the intermediate zone allow air and dust to flow while inhibiting the flow of aggregate. The collection housing surrounding the intermediate zone is of a size such as to produce a reduction in the velocity of the air as it passes out of the drum. Consequently, it serves as a knock-out box for the collection of larger particles which are carried out of the drum, but which settle out of the air stream as a result of the velocity decrease. These collected particles are reintroduced into the drum by scoops on the exterior of the drum. These scoops are also used for the introduction of recycled asphaltic concrete.
U.S. Pat. No. 4,895,451 ('451 patent), which issued to Hockett, discloses a Mixing Device. The '451 patent teaches an improved mixing device for mixing an abrasive such as sand with a flowing fluid such as compressed air. The improved mixing device comprises a body member having a major internal channel being defined along a major axis. The major internal channel extends between a major input and a major output of the major internal channel. The body member includes a minor internal channel defined along a minor axis and extending from a minor input to an intersection with a portion of the major internal channel located between the major input and the major output of the major internal channel. The flowing fluid is directed into the major input whereas the abrasive is directed into the minor input for enabling the abrasive to mix with the flowing fluid within the major internal channel and to discharge from the major output. The minor internal channel is established at an acute angle relative to the major internal channel and extends generally toward the major input of the major internal channel for enabling abrasive erosion of the body member to be distributed over a region of the body member during prolonged use of the mixing device.
U.S. Pat. No. 4,941,599 ('599 patent), which issued to Reinertz et al., discloses a Method and Apparatus for Thoroughly Mixing a Suspension Containing a Fluid and Solid Matter Constituents. The '599 patent teaches an apparatus and a method for thoroughly mixing a suspension containing a fluid and solid matter constituents and spraying the thoroughly mixed suspension onto a surface. The apparatus includes a pressure and seal tight container enclosed on all sides for accommodating the suspension therein. The container has a top region and has a base region whereat the solid matter constituents tend to collect to form a sediment. A cylinder and a piston generate a charge of air under pressure which is conducted through a passage into the base region of the container to break up the sediment and thoroughly mix the solid matter constituents in the fluid as the air under pressure rises through the suspension to collect at the top region of the container where it imparts pressure to the suspension. A nozzle unit mounted on the container vents the container to permit the air under pressure to entrain the thoroughly mixed suspension to form a spray. With the invention, the suspension is always thoroughly mixed for each pumping operation and during the spraying operation so that a loss of function because of blockage of the spray system is prevented.
U.S. Pat. No. 5,002,426 ('426 patent), which issued to Brown et al., discloses a Paddle Mixer for Asphalt Pavers. The '426 patent teaches a revolving paddle mixer for re-mixing a hot asphalt mix deposited in the hopper of a road paving machine. The mixer takes the form of a plurality of paddles angularly positioned relative to each other and mounted on a revolving shaft adjacent to the conveyor for transporting the asphalt mix material to the rotating auger. The resultant re-mixture is more uniform and dense so that a smooth pavement is laid on the roadway.
U.S. Pat. No. 5,009,508 ('508 patent), which issued to Wojdylo, discloses an Apparatus for Mixing Concrete. The '508 patent teaches an abstract for mixing concrete which includes a tank having at least a portion thereof which permits the inside of the tank to be visually observed from the outside of the tank. An inlet is disposed in the top of the tank for inserting concrete ingredients. An outlet is disposed in the bottom of the tank for permitting the mixed concrete to be withdrawn from a chamber inside the tank. The tank includes seals for selectively sealing all openings into the chamber of the tank and an opening is provided for introducing air under pressure into a lower portion of the tank for the purpose of being able to mix the concrete using such air pressure.
U.S. Pat. No. 5,380,082 ('082 patent), which issued to Milstead, discloses an Asphalt Drum Mixer with Curved Scoop-like Mixing Tips. The '082 patent teaches an asphalt drum mixer comprising a rotating drum within a fixed sleeve which defines an annular chamber, and mixing tips mounted on the drum and in the annular chamber. The mixing tips pass through the hot mix asphalt lying in the bottom of the annular chamber and mix and shear the hot mix asphalt and increase its residence time in the drum mixer. In one preferred embodiment, the mixing tips may comprise curved scoop-like elements which lift the hot mix asphalt higher than conventional paddles and greatly increase residence time of the mix in the drum over conventional paddles. The quality of the mix is thus greatly improved. In another preferred embodiment the mixing tips may comprise curved scoop-like elements having slots which greatly increase sheering of the hot mix asphalt, thereby further improving the quality of the mix.
U.S. Pat. No. 5,586,731 ('731 patent), which issued to Glaze et al., discloses a Compost Mixing and Aerating Apparatus. The '731 patent teaches an improved composting apparatus particularly suited for use with straw-like materials. The composting apparatus includes a counter-rotating drum and paddle assembly which generates a plurality of air streams in which the composting material is entrained. The air streams rotate in a vortex like pattern within a chamber to mix and aerate the composting material. The composting apparatus is configurable for being driven sideways through fence gates and the like, and has an additional configuration for being towed without requiring a trailer.
U.S. Pat. No. 5,676,716 ('716 patent), which issued to Gohara et al., discloses an Apparatus for Mixing a Tank and Improving Air/Liquid Contact in an Oxidized System. The '716 patent teaches an apparatus to mix a slurry mixture with an oxidization air within a reaction tank of a wet scrubber spray tower of a flue gas desulfurization system for a furnace. The apparatus improves the contact between forced oxidization air and slurry mixture within the reaction tank. U.S. Pat. No. 5,824,141 ('141 patent), which also issued to Gohara et al., discloses an apparatus to mix a slurry mixture with an oxidization air within a reaction tank of a wet scrubber spray tower of a flue gas desulfurization system for a furnace. The apparatus improves the contact between forced oxidization air and slurry mixture within the reaction tank.
From a consideration of the foregoing disclosures, it may be seen that the prior art discloses complex paddle-type mixers (e.g. the '426 and '082 patents); complex air-type mixers (e.g. the '003, '451, and '599 patents), and simplistic air-type slurry mixers (e.g. the '508 patent). Coal tar sealers, asphalt based sealers, and similar other slurry type mixtures (such as concrete) having heavy (or gravitationally separable) particulate mixed with aggregate are generally easier to blend with air agitation than by conventional paddle agitation. The prior art thus perceives a need for a simplified air-based slurry mixing apparatus and/or methodology, which apparatus and associated method may well function to provide a homogenous slurry mixture at minimized cost and maintenance.